There are many types of core catchers in use today. Some core catchers are integrated into core sampling technologies, and require active energy-powered movement to work. These active core catcher designs can also be very bulky, difficult to manufacture because of their many moving parts, and expensive. Because of their integration with the sampling technologies, they cannot function independently. For example, a sphincter-type core catcher is rotated closed by the final movement of a piston in a piston core sampler. Many passive core catchers also exist, the majority of them functioning using variations of stiff, yet flexible, fingerlike projections that are arranged in a dome shape and may normally be closed, but are pushed open by incoming sediment. One such core catcher resembles an eggshell, is made of hard plastic, has gaps in between the fingers, and has a small opening at the apex, which allows water to drain out during recovery. This “eggshell” design is not suitable for soupy, finer sediment types, as the sediment, or target organisms, can escape through the gaps or the hole in the apex. There are other passive designs that provide more complete closure but they have many moving parts, which are subject to jamming, and are made of metal, which bends easily and is non-inert.